3 * Helper functions for bitmap.h.
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
8 #include <linux/export.h>
9 #include <linux/thread_info.h>
10 #include <linux/ctype.h>
11 #include <linux/errno.h>
12 #include <linux/bitmap.h>
13 #include <linux/bitops.h>
14 #include <linux/bug.h>
17 #include <asm/uaccess.h>
20 * bitmaps provide an array of bits, implemented using an an
21 * array of unsigned longs. The number of valid bits in a
22 * given bitmap does _not_ need to be an exact multiple of
25 * The possible unused bits in the last, partially used word
26 * of a bitmap are 'don't care'. The implementation makes
27 * no particular effort to keep them zero. It ensures that
28 * their value will not affect the results of any operation.
29 * The bitmap operations that return Boolean (bitmap_empty,
30 * for example) or scalar (bitmap_weight, for example) results
31 * carefully filter out these unused bits from impacting their
34 * These operations actually hold to a slightly stronger rule:
35 * if you don't input any bitmaps to these ops that have some
36 * unused bits set, then they won't output any set unused bits
39 * The byte ordering of bitmaps is more natural on little
40 * endian architectures. See the big-endian headers
41 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
42 * for the best explanations of this ordering.
45 int __bitmap_empty(const unsigned long *bitmap
, unsigned int bits
)
47 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
48 for (k
= 0; k
< lim
; ++k
)
52 if (bits
% BITS_PER_LONG
)
53 if (bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
58 EXPORT_SYMBOL(__bitmap_empty
);
60 int __bitmap_full(const unsigned long *bitmap
, unsigned int bits
)
62 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
63 for (k
= 0; k
< lim
; ++k
)
67 if (bits
% BITS_PER_LONG
)
68 if (~bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
))
73 EXPORT_SYMBOL(__bitmap_full
);
75 int __bitmap_equal(const unsigned long *bitmap1
,
76 const unsigned long *bitmap2
, unsigned int bits
)
78 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
79 for (k
= 0; k
< lim
; ++k
)
80 if (bitmap1
[k
] != bitmap2
[k
])
83 if (bits
% BITS_PER_LONG
)
84 if ((bitmap1
[k
] ^ bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
89 EXPORT_SYMBOL(__bitmap_equal
);
91 void __bitmap_complement(unsigned long *dst
, const unsigned long *src
, unsigned int bits
)
93 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
94 for (k
= 0; k
< lim
; ++k
)
97 if (bits
% BITS_PER_LONG
)
100 EXPORT_SYMBOL(__bitmap_complement
);
103 * __bitmap_shift_right - logical right shift of the bits in a bitmap
104 * @dst : destination bitmap
105 * @src : source bitmap
106 * @shift : shift by this many bits
107 * @nbits : bitmap size, in bits
109 * Shifting right (dividing) means moving bits in the MS -> LS bit
110 * direction. Zeros are fed into the vacated MS positions and the
111 * LS bits shifted off the bottom are lost.
113 void __bitmap_shift_right(unsigned long *dst
, const unsigned long *src
,
114 unsigned shift
, unsigned nbits
)
116 unsigned k
, lim
= BITS_TO_LONGS(nbits
);
117 unsigned off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
118 unsigned long mask
= BITMAP_LAST_WORD_MASK(nbits
);
119 for (k
= 0; off
+ k
< lim
; ++k
) {
120 unsigned long upper
, lower
;
123 * If shift is not word aligned, take lower rem bits of
124 * word above and make them the top rem bits of result.
126 if (!rem
|| off
+ k
+ 1 >= lim
)
129 upper
= src
[off
+ k
+ 1];
130 if (off
+ k
+ 1 == lim
- 1)
132 upper
<<= (BITS_PER_LONG
- rem
);
134 lower
= src
[off
+ k
];
135 if (off
+ k
== lim
- 1)
138 dst
[k
] = lower
| upper
;
141 memset(&dst
[lim
- off
], 0, off
*sizeof(unsigned long));
143 EXPORT_SYMBOL(__bitmap_shift_right
);
147 * __bitmap_shift_left - logical left shift of the bits in a bitmap
148 * @dst : destination bitmap
149 * @src : source bitmap
150 * @shift : shift by this many bits
151 * @nbits : bitmap size, in bits
153 * Shifting left (multiplying) means moving bits in the LS -> MS
154 * direction. Zeros are fed into the vacated LS bit positions
155 * and those MS bits shifted off the top are lost.
158 void __bitmap_shift_left(unsigned long *dst
, const unsigned long *src
,
159 unsigned int shift
, unsigned int nbits
)
162 unsigned int lim
= BITS_TO_LONGS(nbits
), left
= nbits
% BITS_PER_LONG
;
163 unsigned int off
= shift
/BITS_PER_LONG
, rem
= shift
% BITS_PER_LONG
;
164 for (k
= lim
- off
- 1; k
>= 0; --k
) {
165 unsigned long upper
, lower
;
168 * If shift is not word aligned, take upper rem bits of
169 * word below and make them the bottom rem bits of result.
172 lower
= src
[k
- 1] >> (BITS_PER_LONG
- rem
);
176 if (left
&& k
== lim
- 1)
177 upper
&= (1UL << left
) - 1;
179 dst
[k
+ off
] = lower
| upper
;
180 if (left
&& k
+ off
== lim
- 1)
181 dst
[k
+ off
] &= (1UL << left
) - 1;
184 memset(dst
, 0, off
*sizeof(unsigned long));
186 EXPORT_SYMBOL(__bitmap_shift_left
);
188 int __bitmap_and(unsigned long *dst
, const unsigned long *bitmap1
,
189 const unsigned long *bitmap2
, unsigned int bits
)
192 unsigned int lim
= bits
/BITS_PER_LONG
;
193 unsigned long result
= 0;
195 for (k
= 0; k
< lim
; k
++)
196 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
]);
197 if (bits
% BITS_PER_LONG
)
198 result
|= (dst
[k
] = bitmap1
[k
] & bitmap2
[k
] &
199 BITMAP_LAST_WORD_MASK(bits
));
202 EXPORT_SYMBOL(__bitmap_and
);
204 void __bitmap_or(unsigned long *dst
, const unsigned long *bitmap1
,
205 const unsigned long *bitmap2
, unsigned int bits
)
208 unsigned int nr
= BITS_TO_LONGS(bits
);
210 for (k
= 0; k
< nr
; k
++)
211 dst
[k
] = bitmap1
[k
] | bitmap2
[k
];
213 EXPORT_SYMBOL(__bitmap_or
);
215 void __bitmap_xor(unsigned long *dst
, const unsigned long *bitmap1
,
216 const unsigned long *bitmap2
, unsigned int bits
)
219 unsigned int nr
= BITS_TO_LONGS(bits
);
221 for (k
= 0; k
< nr
; k
++)
222 dst
[k
] = bitmap1
[k
] ^ bitmap2
[k
];
224 EXPORT_SYMBOL(__bitmap_xor
);
226 int __bitmap_andnot(unsigned long *dst
, const unsigned long *bitmap1
,
227 const unsigned long *bitmap2
, unsigned int bits
)
230 unsigned int lim
= bits
/BITS_PER_LONG
;
231 unsigned long result
= 0;
233 for (k
= 0; k
< lim
; k
++)
234 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
]);
235 if (bits
% BITS_PER_LONG
)
236 result
|= (dst
[k
] = bitmap1
[k
] & ~bitmap2
[k
] &
237 BITMAP_LAST_WORD_MASK(bits
));
240 EXPORT_SYMBOL(__bitmap_andnot
);
242 int __bitmap_intersects(const unsigned long *bitmap1
,
243 const unsigned long *bitmap2
, unsigned int bits
)
245 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
246 for (k
= 0; k
< lim
; ++k
)
247 if (bitmap1
[k
] & bitmap2
[k
])
250 if (bits
% BITS_PER_LONG
)
251 if ((bitmap1
[k
] & bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
255 EXPORT_SYMBOL(__bitmap_intersects
);
257 int __bitmap_subset(const unsigned long *bitmap1
,
258 const unsigned long *bitmap2
, unsigned int bits
)
260 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
261 for (k
= 0; k
< lim
; ++k
)
262 if (bitmap1
[k
] & ~bitmap2
[k
])
265 if (bits
% BITS_PER_LONG
)
266 if ((bitmap1
[k
] & ~bitmap2
[k
]) & BITMAP_LAST_WORD_MASK(bits
))
270 EXPORT_SYMBOL(__bitmap_subset
);
272 int __bitmap_weight(const unsigned long *bitmap
, unsigned int bits
)
274 unsigned int k
, lim
= bits
/BITS_PER_LONG
;
277 for (k
= 0; k
< lim
; k
++)
278 w
+= hweight_long(bitmap
[k
]);
280 if (bits
% BITS_PER_LONG
)
281 w
+= hweight_long(bitmap
[k
] & BITMAP_LAST_WORD_MASK(bits
));
285 EXPORT_SYMBOL(__bitmap_weight
);
287 void bitmap_set(unsigned long *map
, unsigned int start
, int len
)
289 unsigned long *p
= map
+ BIT_WORD(start
);
290 const unsigned int size
= start
+ len
;
291 int bits_to_set
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
292 unsigned long mask_to_set
= BITMAP_FIRST_WORD_MASK(start
);
294 while (len
- bits_to_set
>= 0) {
297 bits_to_set
= BITS_PER_LONG
;
302 mask_to_set
&= BITMAP_LAST_WORD_MASK(size
);
306 EXPORT_SYMBOL(bitmap_set
);
308 void bitmap_clear(unsigned long *map
, unsigned int start
, int len
)
310 unsigned long *p
= map
+ BIT_WORD(start
);
311 const unsigned int size
= start
+ len
;
312 int bits_to_clear
= BITS_PER_LONG
- (start
% BITS_PER_LONG
);
313 unsigned long mask_to_clear
= BITMAP_FIRST_WORD_MASK(start
);
315 while (len
- bits_to_clear
>= 0) {
316 *p
&= ~mask_to_clear
;
317 len
-= bits_to_clear
;
318 bits_to_clear
= BITS_PER_LONG
;
319 mask_to_clear
= ~0UL;
323 mask_to_clear
&= BITMAP_LAST_WORD_MASK(size
);
324 *p
&= ~mask_to_clear
;
327 EXPORT_SYMBOL(bitmap_clear
);
330 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
331 * @map: The address to base the search on
332 * @size: The bitmap size in bits
333 * @start: The bitnumber to start searching at
334 * @nr: The number of zeroed bits we're looking for
335 * @align_mask: Alignment mask for zero area
336 * @align_offset: Alignment offset for zero area.
338 * The @align_mask should be one less than a power of 2; the effect is that
339 * the bit offset of all zero areas this function finds plus @align_offset
340 * is multiple of that power of 2.
342 unsigned long bitmap_find_next_zero_area_off(unsigned long *map
,
346 unsigned long align_mask
,
347 unsigned long align_offset
)
349 unsigned long index
, end
, i
;
351 index
= find_next_zero_bit(map
, size
, start
);
353 /* Align allocation */
354 index
= __ALIGN_MASK(index
+ align_offset
, align_mask
) - align_offset
;
359 i
= find_next_bit(map
, end
, index
);
366 EXPORT_SYMBOL(bitmap_find_next_zero_area_off
);
369 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
370 * second version by Paul Jackson, third by Joe Korty.
374 #define nbits_to_hold_value(val) fls(val)
375 #define BASEDEC 10 /* fancier cpuset lists input in decimal */
378 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
379 * @buf: byte buffer into which string is placed
380 * @buflen: reserved size of @buf, in bytes
381 * @maskp: pointer to bitmap to convert
382 * @nmaskbits: size of bitmap, in bits
384 * Exactly @nmaskbits bits are displayed. Hex digits are grouped into
385 * comma-separated sets of eight digits per set. Returns the number of
386 * characters which were written to *buf, excluding the trailing \0.
388 int bitmap_scnprintf(char *buf
, unsigned int buflen
,
389 const unsigned long *maskp
, int nmaskbits
)
391 int i
, word
, bit
, len
= 0;
393 const char *sep
= "";
397 chunksz
= nmaskbits
& (CHUNKSZ
- 1);
401 i
= ALIGN(nmaskbits
, CHUNKSZ
) - CHUNKSZ
;
402 for (; i
>= 0; i
-= CHUNKSZ
) {
403 chunkmask
= ((1ULL << chunksz
) - 1);
404 word
= i
/ BITS_PER_LONG
;
405 bit
= i
% BITS_PER_LONG
;
406 val
= (maskp
[word
] >> bit
) & chunkmask
;
407 len
+= scnprintf(buf
+len
, buflen
-len
, "%s%0*lx", sep
,
414 EXPORT_SYMBOL(bitmap_scnprintf
);
417 * __bitmap_parse - convert an ASCII hex string into a bitmap.
418 * @buf: pointer to buffer containing string.
419 * @buflen: buffer size in bytes. If string is smaller than this
420 * then it must be terminated with a \0.
421 * @is_user: location of buffer, 0 indicates kernel space
422 * @maskp: pointer to bitmap array that will contain result.
423 * @nmaskbits: size of bitmap, in bits.
425 * Commas group hex digits into chunks. Each chunk defines exactly 32
426 * bits of the resultant bitmask. No chunk may specify a value larger
427 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
428 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
429 * characters and for grouping errors such as "1,,5", ",44", "," and "".
430 * Leading and trailing whitespace accepted, but not embedded whitespace.
432 int __bitmap_parse(const char *buf
, unsigned int buflen
,
433 int is_user
, unsigned long *maskp
,
436 int c
, old_c
, totaldigits
, ndigits
, nchunks
, nbits
;
438 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
440 bitmap_zero(maskp
, nmaskbits
);
442 nchunks
= nbits
= totaldigits
= c
= 0;
446 /* Get the next chunk of the bitmap */
450 if (__get_user(c
, ubuf
++))
460 * If the last character was a space and the current
461 * character isn't '\0', we've got embedded whitespace.
462 * This is a no-no, so throw an error.
464 if (totaldigits
&& c
&& isspace(old_c
))
467 /* A '\0' or a ',' signal the end of the chunk */
468 if (c
== '\0' || c
== ',')
475 * Make sure there are at least 4 free bits in 'chunk'.
476 * If not, this hexdigit will overflow 'chunk', so
479 if (chunk
& ~((1UL << (CHUNKSZ
- 4)) - 1))
482 chunk
= (chunk
<< 4) | hex_to_bin(c
);
483 ndigits
++; totaldigits
++;
487 if (nchunks
== 0 && chunk
== 0)
490 __bitmap_shift_left(maskp
, maskp
, CHUNKSZ
, nmaskbits
);
493 nbits
+= (nchunks
== 1) ? nbits_to_hold_value(chunk
) : CHUNKSZ
;
494 if (nbits
> nmaskbits
)
496 } while (buflen
&& c
== ',');
500 EXPORT_SYMBOL(__bitmap_parse
);
503 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
505 * @ubuf: pointer to user buffer containing string.
506 * @ulen: buffer size in bytes. If string is smaller than this
507 * then it must be terminated with a \0.
508 * @maskp: pointer to bitmap array that will contain result.
509 * @nmaskbits: size of bitmap, in bits.
511 * Wrapper for __bitmap_parse(), providing it with user buffer.
513 * We cannot have this as an inline function in bitmap.h because it needs
514 * linux/uaccess.h to get the access_ok() declaration and this causes
515 * cyclic dependencies.
517 int bitmap_parse_user(const char __user
*ubuf
,
518 unsigned int ulen
, unsigned long *maskp
,
521 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
523 return __bitmap_parse((const char __force
*)ubuf
,
524 ulen
, 1, maskp
, nmaskbits
);
527 EXPORT_SYMBOL(bitmap_parse_user
);
530 * bscnl_emit(buf, buflen, rbot, rtop, bp)
532 * Helper routine for bitmap_scnlistprintf(). Write decimal number
533 * or range to buf, suppressing output past buf+buflen, with optional
534 * comma-prefix. Return len of what was written to *buf, excluding the
537 static inline int bscnl_emit(char *buf
, int buflen
, int rbot
, int rtop
, int len
)
540 len
+= scnprintf(buf
+ len
, buflen
- len
, ",");
542 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d", rbot
);
544 len
+= scnprintf(buf
+ len
, buflen
- len
, "%d-%d", rbot
, rtop
);
549 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
550 * @buf: byte buffer into which string is placed
551 * @buflen: reserved size of @buf, in bytes
552 * @maskp: pointer to bitmap to convert
553 * @nmaskbits: size of bitmap, in bits
555 * Output format is a comma-separated list of decimal numbers and
556 * ranges. Consecutively set bits are shown as two hyphen-separated
557 * decimal numbers, the smallest and largest bit numbers set in
558 * the range. Output format is compatible with the format
559 * accepted as input by bitmap_parselist().
561 * The return value is the number of characters which were written to *buf
562 * excluding the trailing '\0', as per ISO C99's scnprintf.
564 int bitmap_scnlistprintf(char *buf
, unsigned int buflen
,
565 const unsigned long *maskp
, int nmaskbits
)
568 /* current bit is 'cur', most recently seen range is [rbot, rtop] */
575 rbot
= cur
= find_first_bit(maskp
, nmaskbits
);
576 while (cur
< nmaskbits
) {
578 cur
= find_next_bit(maskp
, nmaskbits
, cur
+1);
579 if (cur
>= nmaskbits
|| cur
> rtop
+ 1) {
580 len
= bscnl_emit(buf
, buflen
, rbot
, rtop
, len
);
586 EXPORT_SYMBOL(bitmap_scnlistprintf
);
589 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
590 * @list: indicates whether the bitmap must be list
591 * @buf: page aligned buffer into which string is placed
592 * @maskp: pointer to bitmap to convert
593 * @nmaskbits: size of bitmap, in bits
595 * Output format is a comma-separated list of decimal numbers and
596 * ranges if list is specified or hex digits grouped into comma-separated
597 * sets of 8 digits/set. Returns the number of characters written to buf.
599 int bitmap_print_to_pagebuf(bool list
, char *buf
, const unsigned long *maskp
,
602 ptrdiff_t len
= PTR_ALIGN(buf
+ PAGE_SIZE
- 1, PAGE_SIZE
) - buf
- 2;
606 n
= list
? bitmap_scnlistprintf(buf
, len
, maskp
, nmaskbits
) :
607 bitmap_scnprintf(buf
, len
, maskp
, nmaskbits
);
613 EXPORT_SYMBOL(bitmap_print_to_pagebuf
);
616 * __bitmap_parselist - convert list format ASCII string to bitmap
617 * @buf: read nul-terminated user string from this buffer
618 * @buflen: buffer size in bytes. If string is smaller than this
619 * then it must be terminated with a \0.
620 * @is_user: location of buffer, 0 indicates kernel space
621 * @maskp: write resulting mask here
622 * @nmaskbits: number of bits in mask to be written
624 * Input format is a comma-separated list of decimal numbers and
625 * ranges. Consecutively set bits are shown as two hyphen-separated
626 * decimal numbers, the smallest and largest bit numbers set in
629 * Returns 0 on success, -errno on invalid input strings.
631 * %-EINVAL: second number in range smaller than first
632 * %-EINVAL: invalid character in string
633 * %-ERANGE: bit number specified too large for mask
635 static int __bitmap_parselist(const char *buf
, unsigned int buflen
,
636 int is_user
, unsigned long *maskp
,
640 int c
, old_c
, totaldigits
;
641 const char __user __force
*ubuf
= (const char __user __force
*)buf
;
642 int exp_digit
, in_range
;
645 bitmap_zero(maskp
, nmaskbits
);
651 /* Get the next cpu# or a range of cpu#'s */
655 if (__get_user(c
, ubuf
++))
664 * If the last character was a space and the current
665 * character isn't '\0', we've got embedded whitespace.
666 * This is a no-no, so throw an error.
668 if (totaldigits
&& c
&& isspace(old_c
))
671 /* A '\0' or a ',' signal the end of a cpu# or range */
672 if (c
== '\0' || c
== ',')
676 if (exp_digit
|| in_range
)
687 b
= b
* 10 + (c
- '0');
701 } while (buflen
&& c
== ',');
705 int bitmap_parselist(const char *bp
, unsigned long *maskp
, int nmaskbits
)
707 char *nl
= strchrnul(bp
, '\n');
710 return __bitmap_parselist(bp
, len
, 0, maskp
, nmaskbits
);
712 EXPORT_SYMBOL(bitmap_parselist
);
716 * bitmap_parselist_user()
718 * @ubuf: pointer to user buffer containing string.
719 * @ulen: buffer size in bytes. If string is smaller than this
720 * then it must be terminated with a \0.
721 * @maskp: pointer to bitmap array that will contain result.
722 * @nmaskbits: size of bitmap, in bits.
724 * Wrapper for bitmap_parselist(), providing it with user buffer.
726 * We cannot have this as an inline function in bitmap.h because it needs
727 * linux/uaccess.h to get the access_ok() declaration and this causes
728 * cyclic dependencies.
730 int bitmap_parselist_user(const char __user
*ubuf
,
731 unsigned int ulen
, unsigned long *maskp
,
734 if (!access_ok(VERIFY_READ
, ubuf
, ulen
))
736 return __bitmap_parselist((const char __force
*)ubuf
,
737 ulen
, 1, maskp
, nmaskbits
);
739 EXPORT_SYMBOL(bitmap_parselist_user
);
743 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
744 * @buf: pointer to a bitmap
745 * @pos: a bit position in @buf (0 <= @pos < @nbits)
746 * @nbits: number of valid bit positions in @buf
748 * Map the bit at position @pos in @buf (of length @nbits) to the
749 * ordinal of which set bit it is. If it is not set or if @pos
750 * is not a valid bit position, map to -1.
752 * If for example, just bits 4 through 7 are set in @buf, then @pos
753 * values 4 through 7 will get mapped to 0 through 3, respectively,
754 * and other @pos values will get mapped to -1. When @pos value 7
755 * gets mapped to (returns) @ord value 3 in this example, that means
756 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
758 * The bit positions 0 through @bits are valid positions in @buf.
760 static int bitmap_pos_to_ord(const unsigned long *buf
, unsigned int pos
, unsigned int nbits
)
762 if (pos
>= nbits
|| !test_bit(pos
, buf
))
765 return __bitmap_weight(buf
, pos
);
769 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
770 * @buf: pointer to bitmap
771 * @ord: ordinal bit position (n-th set bit, n >= 0)
772 * @nbits: number of valid bit positions in @buf
774 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
775 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
776 * >= weight(buf), returns @nbits.
778 * If for example, just bits 4 through 7 are set in @buf, then @ord
779 * values 0 through 3 will get mapped to 4 through 7, respectively,
780 * and all other @ord values returns @nbits. When @ord value 3
781 * gets mapped to (returns) @pos value 7 in this example, that means
782 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
784 * The bit positions 0 through @nbits-1 are valid positions in @buf.
786 unsigned int bitmap_ord_to_pos(const unsigned long *buf
, unsigned int ord
, unsigned int nbits
)
790 for (pos
= find_first_bit(buf
, nbits
);
792 pos
= find_next_bit(buf
, nbits
, pos
+ 1))
799 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
800 * @dst: remapped result
801 * @src: subset to be remapped
802 * @old: defines domain of map
803 * @new: defines range of map
804 * @nbits: number of bits in each of these bitmaps
806 * Let @old and @new define a mapping of bit positions, such that
807 * whatever position is held by the n-th set bit in @old is mapped
808 * to the n-th set bit in @new. In the more general case, allowing
809 * for the possibility that the weight 'w' of @new is less than the
810 * weight of @old, map the position of the n-th set bit in @old to
811 * the position of the m-th set bit in @new, where m == n % w.
813 * If either of the @old and @new bitmaps are empty, or if @src and
814 * @dst point to the same location, then this routine copies @src
817 * The positions of unset bits in @old are mapped to themselves
818 * (the identify map).
820 * Apply the above specified mapping to @src, placing the result in
821 * @dst, clearing any bits previously set in @dst.
823 * For example, lets say that @old has bits 4 through 7 set, and
824 * @new has bits 12 through 15 set. This defines the mapping of bit
825 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
826 * bit positions unchanged. So if say @src comes into this routine
827 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
830 void bitmap_remap(unsigned long *dst
, const unsigned long *src
,
831 const unsigned long *old
, const unsigned long *new,
834 unsigned int oldbit
, w
;
836 if (dst
== src
) /* following doesn't handle inplace remaps */
838 bitmap_zero(dst
, nbits
);
840 w
= bitmap_weight(new, nbits
);
841 for_each_set_bit(oldbit
, src
, nbits
) {
842 int n
= bitmap_pos_to_ord(old
, oldbit
, nbits
);
845 set_bit(oldbit
, dst
); /* identity map */
847 set_bit(bitmap_ord_to_pos(new, n
% w
, nbits
), dst
);
850 EXPORT_SYMBOL(bitmap_remap
);
853 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
854 * @oldbit: bit position to be mapped
855 * @old: defines domain of map
856 * @new: defines range of map
857 * @bits: number of bits in each of these bitmaps
859 * Let @old and @new define a mapping of bit positions, such that
860 * whatever position is held by the n-th set bit in @old is mapped
861 * to the n-th set bit in @new. In the more general case, allowing
862 * for the possibility that the weight 'w' of @new is less than the
863 * weight of @old, map the position of the n-th set bit in @old to
864 * the position of the m-th set bit in @new, where m == n % w.
866 * The positions of unset bits in @old are mapped to themselves
867 * (the identify map).
869 * Apply the above specified mapping to bit position @oldbit, returning
870 * the new bit position.
872 * For example, lets say that @old has bits 4 through 7 set, and
873 * @new has bits 12 through 15 set. This defines the mapping of bit
874 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
875 * bit positions unchanged. So if say @oldbit is 5, then this routine
878 int bitmap_bitremap(int oldbit
, const unsigned long *old
,
879 const unsigned long *new, int bits
)
881 int w
= bitmap_weight(new, bits
);
882 int n
= bitmap_pos_to_ord(old
, oldbit
, bits
);
886 return bitmap_ord_to_pos(new, n
% w
, bits
);
888 EXPORT_SYMBOL(bitmap_bitremap
);
891 * bitmap_onto - translate one bitmap relative to another
892 * @dst: resulting translated bitmap
893 * @orig: original untranslated bitmap
894 * @relmap: bitmap relative to which translated
895 * @bits: number of bits in each of these bitmaps
897 * Set the n-th bit of @dst iff there exists some m such that the
898 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
899 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
900 * (If you understood the previous sentence the first time your
901 * read it, you're overqualified for your current job.)
903 * In other words, @orig is mapped onto (surjectively) @dst,
904 * using the map { <n, m> | the n-th bit of @relmap is the
905 * m-th set bit of @relmap }.
907 * Any set bits in @orig above bit number W, where W is the
908 * weight of (number of set bits in) @relmap are mapped nowhere.
909 * In particular, if for all bits m set in @orig, m >= W, then
910 * @dst will end up empty. In situations where the possibility
911 * of such an empty result is not desired, one way to avoid it is
912 * to use the bitmap_fold() operator, below, to first fold the
913 * @orig bitmap over itself so that all its set bits x are in the
914 * range 0 <= x < W. The bitmap_fold() operator does this by
915 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
917 * Example [1] for bitmap_onto():
918 * Let's say @relmap has bits 30-39 set, and @orig has bits
919 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
920 * @dst will have bits 31, 33, 35, 37 and 39 set.
922 * When bit 0 is set in @orig, it means turn on the bit in
923 * @dst corresponding to whatever is the first bit (if any)
924 * that is turned on in @relmap. Since bit 0 was off in the
925 * above example, we leave off that bit (bit 30) in @dst.
927 * When bit 1 is set in @orig (as in the above example), it
928 * means turn on the bit in @dst corresponding to whatever
929 * is the second bit that is turned on in @relmap. The second
930 * bit in @relmap that was turned on in the above example was
931 * bit 31, so we turned on bit 31 in @dst.
933 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
934 * because they were the 4th, 6th, 8th and 10th set bits
935 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
936 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
938 * When bit 11 is set in @orig, it means turn on the bit in
939 * @dst corresponding to whatever is the twelfth bit that is
940 * turned on in @relmap. In the above example, there were
941 * only ten bits turned on in @relmap (30..39), so that bit
942 * 11 was set in @orig had no affect on @dst.
944 * Example [2] for bitmap_fold() + bitmap_onto():
945 * Let's say @relmap has these ten bits set:
946 * 40 41 42 43 45 48 53 61 74 95
947 * (for the curious, that's 40 plus the first ten terms of the
948 * Fibonacci sequence.)
950 * Further lets say we use the following code, invoking
951 * bitmap_fold() then bitmap_onto, as suggested above to
952 * avoid the possibility of an empty @dst result:
954 * unsigned long *tmp; // a temporary bitmap's bits
956 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
957 * bitmap_onto(dst, tmp, relmap, bits);
959 * Then this table shows what various values of @dst would be, for
960 * various @orig's. I list the zero-based positions of each set bit.
961 * The tmp column shows the intermediate result, as computed by
962 * using bitmap_fold() to fold the @orig bitmap modulo ten
963 * (the weight of @relmap).
970 * 1 3 5 7 1 3 5 7 41 43 48 61
971 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
972 * 0 9 18 27 0 9 8 7 40 61 74 95
974 * 0 11 22 33 0 1 2 3 40 41 42 43
975 * 0 12 24 36 0 2 4 6 40 42 45 53
976 * 78 102 211 1 2 8 41 42 74 (*)
978 * (*) For these marked lines, if we hadn't first done bitmap_fold()
979 * into tmp, then the @dst result would have been empty.
981 * If either of @orig or @relmap is empty (no set bits), then @dst
982 * will be returned empty.
984 * If (as explained above) the only set bits in @orig are in positions
985 * m where m >= W, (where W is the weight of @relmap) then @dst will
986 * once again be returned empty.
988 * All bits in @dst not set by the above rule are cleared.
990 void bitmap_onto(unsigned long *dst
, const unsigned long *orig
,
991 const unsigned long *relmap
, unsigned int bits
)
993 unsigned int n
, m
; /* same meaning as in above comment */
995 if (dst
== orig
) /* following doesn't handle inplace mappings */
997 bitmap_zero(dst
, bits
);
1000 * The following code is a more efficient, but less
1001 * obvious, equivalent to the loop:
1002 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
1003 * n = bitmap_ord_to_pos(orig, m, bits);
1004 * if (test_bit(m, orig))
1010 for_each_set_bit(n
, relmap
, bits
) {
1011 /* m == bitmap_pos_to_ord(relmap, n, bits) */
1012 if (test_bit(m
, orig
))
1017 EXPORT_SYMBOL(bitmap_onto
);
1020 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1021 * @dst: resulting smaller bitmap
1022 * @orig: original larger bitmap
1023 * @sz: specified size
1024 * @nbits: number of bits in each of these bitmaps
1026 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1027 * Clear all other bits in @dst. See further the comment and
1028 * Example [2] for bitmap_onto() for why and how to use this.
1030 void bitmap_fold(unsigned long *dst
, const unsigned long *orig
,
1031 unsigned int sz
, unsigned int nbits
)
1033 unsigned int oldbit
;
1035 if (dst
== orig
) /* following doesn't handle inplace mappings */
1037 bitmap_zero(dst
, nbits
);
1039 for_each_set_bit(oldbit
, orig
, nbits
)
1040 set_bit(oldbit
% sz
, dst
);
1042 EXPORT_SYMBOL(bitmap_fold
);
1045 * Common code for bitmap_*_region() routines.
1046 * bitmap: array of unsigned longs corresponding to the bitmap
1047 * pos: the beginning of the region
1048 * order: region size (log base 2 of number of bits)
1049 * reg_op: operation(s) to perform on that region of bitmap
1051 * Can set, verify and/or release a region of bits in a bitmap,
1052 * depending on which combination of REG_OP_* flag bits is set.
1054 * A region of a bitmap is a sequence of bits in the bitmap, of
1055 * some size '1 << order' (a power of two), aligned to that same
1056 * '1 << order' power of two.
1058 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1059 * Returns 0 in all other cases and reg_ops.
1063 REG_OP_ISFREE
, /* true if region is all zero bits */
1064 REG_OP_ALLOC
, /* set all bits in region */
1065 REG_OP_RELEASE
, /* clear all bits in region */
1068 static int __reg_op(unsigned long *bitmap
, unsigned int pos
, int order
, int reg_op
)
1070 int nbits_reg
; /* number of bits in region */
1071 int index
; /* index first long of region in bitmap */
1072 int offset
; /* bit offset region in bitmap[index] */
1073 int nlongs_reg
; /* num longs spanned by region in bitmap */
1074 int nbitsinlong
; /* num bits of region in each spanned long */
1075 unsigned long mask
; /* bitmask for one long of region */
1076 int i
; /* scans bitmap by longs */
1077 int ret
= 0; /* return value */
1080 * Either nlongs_reg == 1 (for small orders that fit in one long)
1081 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1083 nbits_reg
= 1 << order
;
1084 index
= pos
/ BITS_PER_LONG
;
1085 offset
= pos
- (index
* BITS_PER_LONG
);
1086 nlongs_reg
= BITS_TO_LONGS(nbits_reg
);
1087 nbitsinlong
= min(nbits_reg
, BITS_PER_LONG
);
1090 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1091 * overflows if nbitsinlong == BITS_PER_LONG.
1093 mask
= (1UL << (nbitsinlong
- 1));
1099 for (i
= 0; i
< nlongs_reg
; i
++) {
1100 if (bitmap
[index
+ i
] & mask
)
1103 ret
= 1; /* all bits in region free (zero) */
1107 for (i
= 0; i
< nlongs_reg
; i
++)
1108 bitmap
[index
+ i
] |= mask
;
1111 case REG_OP_RELEASE
:
1112 for (i
= 0; i
< nlongs_reg
; i
++)
1113 bitmap
[index
+ i
] &= ~mask
;
1121 * bitmap_find_free_region - find a contiguous aligned mem region
1122 * @bitmap: array of unsigned longs corresponding to the bitmap
1123 * @bits: number of bits in the bitmap
1124 * @order: region size (log base 2 of number of bits) to find
1126 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1127 * allocate them (set them to one). Only consider regions of length
1128 * a power (@order) of two, aligned to that power of two, which
1129 * makes the search algorithm much faster.
1131 * Return the bit offset in bitmap of the allocated region,
1132 * or -errno on failure.
1134 int bitmap_find_free_region(unsigned long *bitmap
, unsigned int bits
, int order
)
1136 unsigned int pos
, end
; /* scans bitmap by regions of size order */
1138 for (pos
= 0 ; (end
= pos
+ (1U << order
)) <= bits
; pos
= end
) {
1139 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1141 __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1146 EXPORT_SYMBOL(bitmap_find_free_region
);
1149 * bitmap_release_region - release allocated bitmap region
1150 * @bitmap: array of unsigned longs corresponding to the bitmap
1151 * @pos: beginning of bit region to release
1152 * @order: region size (log base 2 of number of bits) to release
1154 * This is the complement to __bitmap_find_free_region() and releases
1155 * the found region (by clearing it in the bitmap).
1159 void bitmap_release_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1161 __reg_op(bitmap
, pos
, order
, REG_OP_RELEASE
);
1163 EXPORT_SYMBOL(bitmap_release_region
);
1166 * bitmap_allocate_region - allocate bitmap region
1167 * @bitmap: array of unsigned longs corresponding to the bitmap
1168 * @pos: beginning of bit region to allocate
1169 * @order: region size (log base 2 of number of bits) to allocate
1171 * Allocate (set bits in) a specified region of a bitmap.
1173 * Return 0 on success, or %-EBUSY if specified region wasn't
1174 * free (not all bits were zero).
1176 int bitmap_allocate_region(unsigned long *bitmap
, unsigned int pos
, int order
)
1178 if (!__reg_op(bitmap
, pos
, order
, REG_OP_ISFREE
))
1180 return __reg_op(bitmap
, pos
, order
, REG_OP_ALLOC
);
1182 EXPORT_SYMBOL(bitmap_allocate_region
);
1185 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1186 * @dst: destination buffer
1187 * @src: bitmap to copy
1188 * @nbits: number of bits in the bitmap
1190 * Require nbits % BITS_PER_LONG == 0.
1193 void bitmap_copy_le(unsigned long *dst
, const unsigned long *src
, unsigned int nbits
)
1197 for (i
= 0; i
< nbits
/BITS_PER_LONG
; i
++) {
1198 if (BITS_PER_LONG
== 64)
1199 dst
[i
] = cpu_to_le64(src
[i
]);
1201 dst
[i
] = cpu_to_le32(src
[i
]);
1204 EXPORT_SYMBOL(bitmap_copy_le
);